percentage calculation: Total amount of a product =29.99(i.e 28.03 + 7%)

[brian147]

Hi,
Total amount of a product =29.99(i.e 28.03 + 7%).
25% off on 29.99=22.50
What is the %off i will have to give on 28.03 so that (28.03-<%off>)+7% tax=22.50
Rather than experimenting and checking the % manually, can someone please tell me if there any fixed formula to arrive at the same?

Thanks,

Brian

 

[Otis]

Total [dollar] amount of a product = 29.99 (i.e., 28.03 + 7%).

25% off on 29.99 = 22.50

I note that, here, you have added the tax before applying the discount.

There appears to be a rounding error.

25% of 29.99 is 7.50

29.99 - 7.50 = 22.49

What is the %off [that I] will have to give on 28.03 so that (28.03 - %off) + 7% tax = 22.50

I note that, here, you have applied the discount before adding the tax.

If you discount 28.03 by 25%, the result is 21.02

7% tax on 21.02 is 1.47

21.02 + 1.47 = 22.50

Hence, %off = 25%

please tell me if there [is] any fixed formula to arrive at the same

X = 1 - T/[(S)(1 + R)]

where

X = discount rate in decimal form

T = desired total

S = beginning subtotal

R = tax rate in decimal form


Cheers :cool:

 

[Otis]

As an afterthought, if you're trying to find a discount rate such that applying the discount before the tax yields the same result as applying the tax before the discount, then you need to carry additional decimal places in the discount rate.

In other words, if you answer 25.01% versus 25%, then the total will be 22.49 instead of 22.50.

You can use the formula, to see this.